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Mar 31, 2013, 03:35 AM
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More optical flow hovering


As bad as optical flow is at absolute position, it's hovering for around 90 seconds at 0.5m before slipping off the floor pattern. Above 1m, it slips off after 1 minute. At 1.5m, it slips off after 30 seconds. Most of the slippage seems attributable to fixed point math errors. The Maxbotix falls apart at 1.5m over posterboard.

Foaming the IMU & applying some fixed point integral magic made the attitude real stable. It's unbelievable how stable that thing became, comparable to the Blade MCX.

If scaling pixels to distance based on altitude must be done in fixed point, it's another area which would be best done with a lookup table instead of getting the angle, getting the tangent & multiplying by the altitude. Horizontal distance also needs a lot more precision than 1/256 meters. There are many navigation routines where fixed point dictates combining many steps in high level lookup tables instead of using discrete trig functions.

Stability is still comparable to the 20 second hover in the px4flow demo video. Time for some waypoints.
Last edited by Jack Crossfire; Mar 31, 2013 at 03:50 AM.
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